Railway signal system



Dec. 18, 1934. J, A. PARKINSON RAILWAY SIGNAL SYSTEM Filed Dec. 17, 19513 Sheets-Sheet 1 III]: INVENTOR. James A Par/ 156125012.

111.5 ATTORNEY.

5 Sheets-Sheet 2 J. A. PARKINSON RAILWAY SIGNAL SYSTEM Filed Dec. 17,1931 Dec. 18, 1934.

R93 WNAQRND 11v VENTOR. James A Parliinsmz 5 His ATTORNEY.

1360- 3 J A. PARKINSON RAILWAY SIGNAL SYSTEM Filed Dec. 1'7, 1931 3Sheets-Sheet 3 IN VENTOR. James/J. Parkinson HIS ATTORNEY.

Patented Dec. 18, 1934 PATENT o ncE James A. Parkinson, Topeka, Kans.

Application'December 17, 1931, Serial No. 581,546.

14 Claims. (Cl.'24633) My invention relates to railway'sign'al systems,

and particularly to railway signal systemsgoverning traific in bothdirections over a stretch of.

railway track.

I will describe one form of system embodying my invention, and will thenpoint out the novel features thereof in claims. 1

Figs. 1, 2 and 3, when placed end to .end in the order named, constitutea diagrammatic view of one form of system embodying my invention whenapplied to a stretch of railway extending between two passing sidingsdesignated by the reference characters P1 and P2.

In describing my invention, reference is made to the accompanyingdrawings wherein like characters of reference designate correspondingparts with a prefix or sufiix added to the reference character in manyinstances to designate the location. In certain instances a circuitcontrolling contact is located on the drawings at a point remote fromthe relay controlling the contact inorder to simplify the disclosure asmuch as possible inorder that it may be more readily understood. In eachinstance, such circuit con-, trolling contact is given a referencecharacterhaving a prefix corresponding to the reference character forthe relay controlling the contact, and the position in which the contactis shown corresponds to the normal condition of the relay.

For example, the circuit controllingfront con tact designated by thereference character B1TR of Fig. 1 is operated by the track relay BlTRand the contact is shown closed inasmuch as the relay BITE is normallyenergized. I shall assume the right-hand end of each view to be east andthe left-hand end to be west, and I shall speak oftraffic moving fromthe right to the left as westbound trafiic and that moving from the leftto the right as eastbound traflic.

- The traffic rails 1 and 2 are divided into track blocks AB, B-C, CDand D-E by the usual insulated rail joints in the customary manner. Eachtrack block is divided into two track sections as will be understood byan inspection of Figs. 1, 2 and 3. In the trackblock CD-there trafiicrails 1 and 2 at one end of the section, and a track relay TR with aprefix corresponding to the location connected to the rails at theopposite end of the section. In connection with the track section at theeast end of the passing sid- 5:

ing P1, the track reI'ayA2 TR is provided with a pick-up circuit thatincludes a back contact GR of a trafilc direction controlling relay GRto be later referred to, and also with a stick circuit that includes itsown front contact 92 as will be 10;

readily understood by an inspection of Fig. 1. It follows that once thetrack section at the switch 1S of siding P1 is occupied and track relayAZTR shunted, the relay can be reenergized only when the trafiicdirection controlling relay GR is deenergized to close the backcontactGR The function of this feature in the controlling of the. trackrelay AZTR will appear later in the specification. I

The switch controlled relay 1SKR associated with the switch 1S forthepassing siding P1 is energized through contacts of a switch circuitcontroller operated by the movement of the switch IS in the manner wellunderstood in the art. That is to say, with switch 1S set for main linetrafiic, the relay 1SKR. is energized by current of one polarity andwhen switch is is set for .trafiic' to the siding P1, the relay 1SK R isenergized with current of a reverse polarity. In a likemanner, theenergizing of the switch controlled relay ZSKR is governed by themovement of the switch for the siding P2. j

At each location A, B, C, D, and E there is located an eastbound signaldesignated by the reference character R plus a SllfilX corresponding tothe location, and a west-bound signal L with a sufiix' corresponding tothe location. These signals may be of any standard type and are hereshown as three-position searchlight signals. As the mechanisms of thesignals form no part of my invention, it is deemed suflicient forthisdescription to point out only the general operation of the signalmechanism. Referring to the signal RB, for example, a spectacle armdesignated by the dotted lines 88 is provided at its upper end withthree different colored filters 12, 13 and 14 and is operated by thearmature 15. The armature 15 is normally biased by means not shown to aposition where the filter 13, which is colored red, is brought inalignment with a light 4 and the signal 0 RB displays a stop indication.The field winding. 16 is permanently connected to a local source ofdirect current not shown but indicated on the drawings by the referencecharacter X for the positive terminal and by the reference character Yfor the negative terminal. With field winding 17 energized with directcurrent of one polarity in a manner to be later pointed out, thearmature 15 is rotated in a clockwise direction until filter 14, whichis colored yellow, is brought in alignment with the light 4 and signalRB displays a caution indication. With field winding 17 energized withcurrent of a reverse polarity, the armature 15 is rotated in acounterclockwise direction'untilfilter. 12, which is colored green,isaligned with light 4 and signal RB-displays a clear indication. Thearmature 15 also actuates two circuit controllers l8 and 19 attachedtothe armature 15 as indicated by: dotted lines. Each of the waysidesignals of my system operate in the same manner as that just describedfor signal RB.

While the light 4 may be illuminated in different ways, a preferred formof lightingcircuits is that where the light is normally supplied withcurrent froman alternating current transmission line, and a localstandby source of direct current isto be automatically cut into servicein the case ofa loss of-alternating current power. Thelight 4' of signalRB is normally supplied-with current from the secondary 5 of atransformer T, the primaryfiofwhich-is continuouslysupplied withalternating currentffrom a transmission line not shown. The circuitforthe light 4. extends fromtone-termina-l of' the secondary 5 through thebackcontact LBBP of a relay LBBP associated with-the westbound signal LBas will be described later, front. contact 8 off a power-off relay PTwhose. winding ispermanently connected to secondary 5', light 4' andfront contact 9' to the other terminal'ofxsecondary 5. In' case of aloss of power from the transmission line, the relay PT is.deenergized'and its contacts 8 and 9 drop into engagement with back contacts. andthe light. 4 is then supplied from a local standby source of directcurrent not shown, but whose terminals aredesignate d by the referencecharacters X and Y; The light circuit now extends from the positiveterminal of the source of direct current, back contact. RBGE of a relayRBGE to. be referred to later,

resistance unit 11,,back. contact '8 of relay PT, light 4, back contactQ'and. to the negative terminal Y. of the source of direct current; Aswill appear later, the. back contacts LBBP 'and RBGE are closedonly uponthe'approach of a train and thus the signal RB is approach lighted bothwhen'the source of current is the alternating currenttransmissionline'and when the" localstandby direct current source is" active; The'lighting circuits forithe westbound signal LB'at'the samelocation B areshownin Fig. land are similar'to those just describedforthe signal RB,an'dthusit is thought notnecessary to describethem in detail. It is'tobe" noted, however, that the alternating" current circuitisnormallyheldopenat the backcontact RBBP 'of:a relay RBBP associated-with theeastbound signal RB, and thecircuit to thedirect current sourceis'normally" held open at the back contact LBGE of a relayLBGEassociated with acontrol'circuit for signal LC to the rear'of signalLBlas will appear as'the'specification progresses. As the light circuitsfor-the'other'signals of my system-are similar tothose described for thesignals at thelocation'B andasthese ligi t circuits form nopart ofmy-invention, the light circuits for the'remainingisignals are not shownin the drawings for-thesake'ofsimplicity. Attention is calledto'thefact, however; that at any intermediate signal location suchas'looation C, the relay LCBP associated with the westbound signal LCis-normally deenergized at a time when the signal RC is cleared foreastbound traffic in a manner to be later pointed out. Thus the lightcircuit not shown for the signal RC, which includes a back contact ofthe relay LCBP in the same manner that the light circuit for the signalLB includes the back contact RBBP is closed normally and the lightcontinually illuminated. When the local standby source of current isactive, however, at such locations, the signal is approach lighted inthesamemanner as isdescribed'above'for the signal RB.

Associated with each wayside signal are two relays designated by thereference characters HD and NP with prefixes corresponding to thesignal. Referring to signal RB, the relay RBI-ID is supplied withcurrentfrom the positive terminal X of the local source of currentthrough the controller 18 in either its lower position corresponding tothe clear position of signal RB or through its upper positioncorresponding to the caution position of signal RB, and the winding ofthe relay to the negative terminal Y of the source of current. The relayRBNP is supplied with current from the positive terminal X throughcontroller 19 in its center position corresponding to the stop positionof signal RB and the winding of relay RBNP to the negative terminal Y.It follows that relay RBI-ID is energized under'both' the clear andcaution positions of signal RB and" deenergized under the stop position,while relay,

RBNP is energized only when signal RB" indicates stop. The relay RBI-IDis made slowreleasing in order that it will remain energized duringthe-interval the signal RB is moved from its caution to clear positionor from its clear to caution position.

Each wayside signal is provided with a control circuit. Looking atsignal LC of Fig. 2, for example, the control circuit for this signalcanbe traced from the battery 21 at location B through the winding of thelow resistance relay LBGE,

front contact RBNP of relay RBNP associated with the signal RB, backcontact 23 of relay LBI-ID, front contact B1TR of track relay BlTR',

line wire 24, frontcontact C2TR of track relay CZTR, front contactWFC ofa directional relay WFC to be described later, field. winding 27 ofsignal LC, line wire 28, back contact 29 of relay LBHD and to theopposite terminal of battery 21. It is to be noted that this controlcircuit for signal LC is governed by the directional relay WFC, by thetrack. circuits for the track block BC and by the relay RBNP governedbythe position of the opposing signal RB. The polarity of the currentsupplied to this control circuit for signal LC is governedby the relayLBl-ID'associated with the westbound signal LB in advance. With thesignal LB at stop and relay LEI-ID deenergized, the current is of onepolarity and. when signal LB is operated to its caution or clearposition and relay LBHD energized, the current supplied to the controlcircuit for signal LC is of a reverse polarity. That is to say, signalLC will display a.

clear indication when the signalLB in advance displays either caution orclear and will display a caution indication when signal LB is at stop.When the immediate track sections in advance of signal LC are occupiedor the opposing signal RB. cleared, signal LC is set at stop. Also, thesignal LC is manually controlled by means of the directional relay WFCas will shortly appear.

The'winding' of the low resistance relay LBGE being in series with thecontrol circuit for the signal LC, it will be energized whenever thatcircuit is closed. The relay LBGE is also'provided, however, with anadditional energizing circuit that includes battery 21, winding of relayLBGE, front contact RBBP of the relay RBBP, high resistance31 and backto the battery 21. Except under trafnc conditions to be later described,the relay LBGE is'retained energized by this last circuit irrespectiveof the condition of the control circuit for signal LC. 7

Each signal of my system'is governed by a control circuit similar tothat just described for the signal LC except at certain locations aswill now be'poi'nted out. The control circuit for the starting signalsRAl and RA2 at the passing siding P1 receives current from the battery32 at location B through the winding of the relay RBGE., front contactLBNP of the relay LBNP, pole-changing contact 114 of relay RBHD, a trackcircuit controlled contact BZTR. of track relayB2TR, front contact lilFBof a directional relay EFB to be shortly described, front contact A1TR'of track relay AlTR, front contact A2'I'R of track relay A2TR, front,contact GB of the direction con-- trolling relay GR, polar contact GR,frontcon tact ISKR of relay ISKR, polar contact ISKR,

field winding 41 ofsignal'RAl and back to' the battery 32 over the linewire 42 through the polechanging contact115. With the polar contact ISKRshifted to the left-hand position in response to the positioning of theswitch 18 for trafiic to the siding P1, this control circuit is thenconnected tothe field winding 43 of the signal RA2 aswill be readilyunderstood from Fig. 1. The control circuit forrthe starting signals LElI and LE2 at the passingsiding P2 is modified from that "described forthe intermediate signals by the including of a contact 44 of a trafficdirection controlling lever 45 and by havingthe circuit first control apolarized relay 46in place of the field winding of the signals directly.With relay 46 energized by one polarity of. current, a circuit is closedfrom the positive terminal X of ,a local source of current through theright-hand polar contact 47, front contact 48, a contact 49 governed bya lever of an interlocking machine not shown, in the usual manner, frontcontact 25KB, righthandpolar contact 2SKR field winding 52 of j signalLE front contact 53, right-hand polar contact 54 of relay 46 and to thenegative terminal Y. With relay 46 energized by current of vareverse'polarity then the current supplied to the field winding 52 willbe, in turn, of reverse polarity. When the switchZS is set for trafiicto the siding P2, the polar contact 2SKR is reversed and relay 46 thencontrols the field winding 55 of signal LE2. V

Across the signal control circuit, in parallel with the field winding ofeach intermediate signal, is connected the winding of a relay designatedby the reference character BP plus a prefix corresponding to the signal.This relay, however, is connected across the control circuit in advanceof the front contact governed by the directional relay. Referring tolocation C, the relay LCBP associated with the control circuit forsignal LC' described above is connected to the line wire 24' directionalrelay WFC, the relay LCBP is governed by trafiic conditions alone. Asstated above, the control circuit m each intermediate signal governs arelay BP in the same manner as just described for' relay LCBP.

In the figures the apparatus is shown set for eastbound trafiic. Themanner of establishing the direction of trafiic will now be described.Each track block is provided with a traffic control 'circuit and twodirectional relays, one for each direction of traffic, designated by thereference character F plus a prefix corresponding to the direction and asuffix corresponding to the location. These trafiic control circuits aregoverned by a trafiic direction controlling device located at each ofthe opposite ends of the stretch of railway. At the passing siding P1,the trafiic direction controlling device is the polarized direct currentrelay GR which is so constructed in a manner Well known to the art thatits polar cona matter of fact, the relay GRmay be replaced] by acontroller actuated by a lever of an interlocking machine should it seemdesirable to do so. At the siding location'P2, the traffic directioncontrolling device is shown in the form of a' manually operated lever 45which actuates the controller contacts 44 and 56. Should it seemdesirable to do so this lever 45 may be replaced by a relay similar tothe relay GR at the opposite end' of the stretch. When lever 45 occupiesits right hand position, that is, the position shown in Fig. 3,'thecontact 56 engages both contact springs 57 and 58. When lever 45 isshifted to its center position or to its left-hand position, the contact56 becomes disengaged from spring 58 and the circuit controlled therebyis opened.

To establish eastbound traflic the operation must begin at the east endof the stretch and proceed as follows: Assuming the track block D--E tobe unoccupied, the relay RDBP at the signal location D will beenergized, as will be evident by an inspection of Fig. 3 due to the factthat the front contacts DlTR EZTR and ElTR of track relays DlTR, E2TRand ElTR, respectively, are closed. The operator moves thetrafl'ic'direction controlling lever 45 to its right-hand position andcurrent is supplied from battery 65 through the front contacts LE2NP andLE1NP in series, contact spring 5'7, contact 56, contact spring 58,linewire 66, back contact 67 of westbound directional relay WFD, frontcontact RDBP of relay RDBP, winding of eastbound directional relay EFDand line wire 68 back to the battery 65. As directional relay EFDbecomes energized, it closes at its front contact 69 a stick circuitaround the front contact RDBP. That is to say, the directional relay EFDcan be picked up only in the event the track block D-E is unoccupied andthe westbound starting signals LE1 and LE2 are at stop, but once it ispicked up, a stick circuit is closed that retains the directional relayEFD energized regardless of the trafiic conditions of the track blockD-E. As directional relay EFD is energized, it also closes front contactEFD'"! included in the signal control circuit for the signal RD and thatsignal is then operated to either its caution or clear positiondepending upon the polarity of the current supplied to its controlcircuit as determined by the position of relay REI-ID' associatedwiththe signal RE in advance.

With track block CD unoccupied so that'its:

track relays ClTR and DZTR are both picked up toclose contacts ClTR andD2TR respectively, and the westbound signal LD is at stop so that therelay LDNP is energized to close front contact LDNP the relay RCBP atlocation C is energized by the control circuit of signal RC. Under thesecircumstances the energizing of the directional relay EFD closes thetraffic control circuit for the block CD from battery '74 through frontcontact '75 of relay EFD, line wire 76, back contact '77 of theWestbound directional relay WFC, front contact RCBP winding of relayEFC, line wire '79, front contact 80 and to the opposite terminal ofbattery 74. As the directional relay EFC picks up, the stick circuitthrough its own front contact 113 is closed around the front contactRC'BP to retain this directional relay energized regardless of trackconditions for the block C-D. Again it is to be noted that beforethe'eastbound directional relay EFC can be energized both the trafficconditions for the track blockC-D and the position of the opposingwestbound signal LD are checked but after the relay EFC is onceenergized, neither the position of signal LD nor the traffic conditionsof the block C-D affect the relay. As directional relay EFC is pickedup, the front'contact EFC is closed to complete the signal controlcircuit to signal RC and that signal is operated inaccordance with theposition of therelayRDI-ID for the signal RD in advance.

With the track block B-C unoccupied and the westbound signal LC at stop,current is'supplied to the relay RBBP at location B by the controlcircuit for signal BB in the same-manner as de-- scribedfor the relayRCBP at the location C and relay RBBP energized to close the frontcontact.

RBBP included in the circuit for relay EF'B. Under these circumstancescurrent flows-from the battery 83 at location C through a trafficcontrol circuit that includes the front contacts 84 and 85 ofdirectional relay EFC to energize the eastbound directional relay EFB atlocation B. This trai'fic control circuit is similar to that alreadydescribedfor the relay EFC and can be easily traced. As directionalrelay EFB picks up, a stick circuit is closed through its own frontcontact 86 to retain this relay energized regardless of trafficconditions for the track block BC or of the position of the opposingsignal LC. The energizing of relay EFB closes the front contact EF'B inthe control circuit for signal RB and current is supplied to the fieldwinding 17 of signal RB to operate that signal in accordance with theposition of the signal RC in advance.

Assuming the track block AB to be unoccupied and that the operator hasenergized the direction controlling relay GR with normal polarity ofcurrent to close the contacts GR and GR The energizing of thedirectional relay EFB closes the contact EFB and thus completes thesignal control circuit to signals RAl and RA2; the circuit being closedto field winding 41 of signal RAl if the switch is is set for main linetraffic and closed to field winding 43 of signal RA2 if switch 18 isreversed for trafiic to the siding P1.

To sum up thus far, the setting of the direction controlling devices ateach end of the stretch of railway in a position corresponding toeastbound traffic causes the traffic control circuits, starting at theeast end of the stretch, to be closed successively to energize in turnan eastbound directional relay at each signal location,

if each successive track section of the stretch" is unoccupied and eachsuccessive opposing westbound signal is set at stop. When once the di--rectional relays are energized, they are retained energized by stickcircuits that make them free from the control of traffic conditions ofthe track sections and also free from the control exerted by theposition of the opposing westbound signals. The energizing of eachdirectional'relay completes a signal control circuit for a correspondingeastbound signal to clear that signal in accordance with trafficconditions in advance. It will be noted that while the operator of therelay GR has control over the starting eastbound signals RAl and RA2, hehas no control over the remaining eastbound signals once they have beencleared for an eastbound train. Also it is to be noted that due to thefact the pick-up circuit for the track relay AZTR is controlled throughthe back contact GR of the relay GR, it is necessary for the operator ofrelay GR, to, actuate that relay in order to clear either startingsignal RAl or RAZ for each following eastbound train as well as for thefirst eastbound train.- It is evident that once eastbound. trafiic hasbeen established, all following eastbound trainswill be governed by theautomatic signals in accordance with trafiic conditions in advance inthe same manner as obtained in the usual three-block automatic signalsystem. As each.

eastbound train leaves location A, the shunting of the relay AlTR opensfront contact A1TR and deenergizes the relay LBBP to approach light thesignal RB by closing the back. contact LBBP" when the normal alternatingcurrent source of current is active. In case thereis a loss ofalternating current power, the signal RB is approach lighted by thestandby current source through the back contact RBGE due to the factthat as relay LBBP becomes deenergized, the

front contact LBBP is opened and relay RBGE deenergized inasmuch as theeastbound train has shunted the track relay AZTR to also. open frontcontact AZTR To reverse the direction of traiiic from that for eastboundtrains, in which condition theapparatus of Figs. 1, 2 and 3 is shown, tothat for westboundtrains, the operator of lever 45 must first reversethe lever to open the circuit to the directional relay EFD. Thedeenergizing of relay EFD sets-signal RD at stop and opens the circuitto relay EFC at the contacts '75 and 80. Relay EFC, in turn, isdeenergized to set the signal RC at stop and open the circuit to thedirectional relay EFB. As relay EFB becomes deenergized, the signal RBis set at stop and the control circuit to the signals RAl and RA2openedv at contact EFB to hold thesesignals at stop. Assuming that thereis no train occupyingthe stretch between the sidings each BP relayassociated with the westbound signal control circuits will be energizeddue to'the fact that the track relays are all picked up and each NPrelay associated with the eastbound signals are now energized checkingthe stop position of the eastbound signals. The operator-at the sidingPl, that is, at the west end of the stretch, energizes the traflicdirection controlling relay GR by current of reverse polarity so thatcontact 95 is made to engage its left-hand contact and current flowsfrom the battery 96 through contact 97 of relay RNP, left-hand contact95, line wire 98, back contact 99 of the eastbound directional relayEFB, front contact LBBP winding of directional 21,9 4,840 relay and line.wire 101 back to the battery 96. As relay WFB picks up, its stickcircuit is closed at front contact 102 to retain that relay energizedirrespective of trafiic conditions of the track block A-B. The signalcontrol circuit for signal LB is now completed at the front contact 4WFB and that signal operated to either the caution or clear positiondepending upon the position of the signal LA in advance. The energizingof the directional relay WFB also closesthe trafiic control circuit forthe block B-C from the battery 103 to thedirectional relay WFC at thefront contacts 104 .and 105 as will be easily traced. This trafiiccontrol circuit being completed through the front contact LCBP of relayLCBP if the opposing eastbound signal RB is at stop so that the contactRBNP of relay RBNP is closed and track relays BlTR and C2TR are pickedup to close contacts B1TR and C2TR respectively. As directional relayWFC picks up, it closes its stick circuit at the contact 10'? around thefront contact LCBP so that this relay is now retained closedirrespective of the trafiic conditions of the track block B-C or of theposition of the opposing signal RB. The

signal control circuit for signal LC is now completed at the frontcontact WFC and that signal operated in'accordance with the position ofthe relay LBHD for signal LB. The energizing of relay WFCalso completesthe trafiic control circult to the. directional relay WFD at the frontcontacts '77 and 10350 that that relay is now supplied with current fromthe battery 83 through the front contact LDBP if block CD is unoccupiedand signal R .at stop.v As relay WFD is energized, its stick circuit isclosed at the contact 109 and it is held energized irrespective oftrafilc conditions in the track block C'D or of the position of theopposing signal RC. The contact WFD is now closed to complete'thecontrol circuit for the signal LD and that signal operated inaccordancefiwith' the position of the relay LCHD for the signal -LC. Asrelay WFD picks up, the control circuit for the relay 46 is also closedat the contact WFD. contact 1l1-44112 being closed because lever 45 isin its reversed position, and that relay energized in accordance withthe position of the relay LDHD for the signal LD. Theenergizingof therelay 46 permits current to be supplied to either the signal LE1 or LE2as determined-by the position of the switch 2S, it being understood, ofcourse, that the lever controlled contact 49 is closed at this time.'With westbound traflic thus established, westbound trains can advancefrom the location E at the passing siding P2 under the protection of thewestbound signals which are now controlled in the usual manner for athreeblock automatic signal system; the westbound directional relaysremaining energized through the medium of their stick circuitsirrespective of the traflic conditions or of the position of theeastbound signals.

It follows from the foregoing description that in establishing agivendirection of traffic, the directional relays corresponding to thedirection of trafiic to be established can be energized only in theevent each track section is unoccupied and the opposing signals all inthe stop position. Once the direction of trailic isestablished thedirectional relays remain energized irrespective of the trafiicconditions. It is to be noted also that a directional relay can beenergized only in the event the opposing directional relay at the samelocation. is deenergized. For example, the cir- -position for a fewseconds.

cuit to relay WFC is controlled by the back contact 84 of thedirectional relay EEG and the circuit for the relay EFC is likewisecontrolled by the back contact 77 of relay WFC.

In the case it is desired to have two trains meet at the siding P3located in the track block C--D, with the westbound train taking thesiding, the procedure is as follows: The two operators will first setthe relay GR and the lever 45 in the positions to establish westboundtraflic in the manner described above and the westbound train advancedfrom the location E to siding P3 by the clearing of the westboundsignals. As this train clears the main track at the siding P3, theoperators set the relayGR and the lever 45 in the position to establisheastbound traffic and the eastbound train advanced to the siding P3 bythe clearing of the eastbound signals. In order to permit the westboundtrain to leave the siding P3 and advance west as soon as the eastboundtrain passes the west end of siding P3, the operator of the lever 45will place the lever in the center This will drop the eastbounddirectional relays and then if the operator of the relay GR reversesthat relay, the westbound directional relays will be energized up to thetrack block 0-D occupied by the east- ,bound'train to clear thewestbound signals from signal LC to the location A. The operator of thelever 45 again places this lever in the right-hand position whichreenergizes the directional relay EFD to again clear the signal RD forthe eastbound train. It follows that these two trains can advance intheir corresponding directions from the siding P3 under full signalprotection. It

would be necessary for the crew of the train on the siding P3 to advisethe. operators when to execute this operation but this could easily beaccomplished by telephone without delay to either train. If theeastbound train is to take siding at P3 the procedure is to establisheastbound traffic to allow the eastbound train to advance to siding P3and then reverse the direction of traffic and advance the westboundtrain. If a work train ora pusher engine stops at any intermediate pointbetween the two sidings P1 and P2, the operators can reverse thedirection of traific to permit this work train or pusher engineto returnto its starting point under full protection of the signals. Once thedirection of traffic is established to advance an eastbound train fromthe siding P1, switching movements can be made at the west end of thesiding P2 without interfering with the eastbound direction of trafficestablished and thus without delaying the eastbound train but stillproviding it with the usual automatic signal protection as it approachesthe siding P2. In the same manner, switching movements can be made atthe east end of the siding Pl after westbound traific hasbeen'established .for a westbound train.

Such a signalsystem as here disclosed checks the occupancy of each tracksection and the stop position of each opposing signal before thedirection of trafiic can beestablished. Once the direction of traflicis, established the system is free from the danger of a loss of trafficdirection due to the possible momentary loss of shunt of a track circuitby. a light engine or motor car. Trains may meet at intermediate pointsand then proceed in opposite directions from the meeting point withoutdelay to either train and under full automatic signal protection. Atrain may reverse its direction of travel at any intermediate point andthe operators establish the direction of trafiic corresponding to thisreverse movement. Once a train has entered the stretch of railway noopposing train movement can be authorized until the occupying train hascleared the stretch of railway. The direction controlling device may beoperated by a centralized trafiic control system, a remote controlsystem, or by a local circuit. In fact, any one system may be used tocontrol the traific controlling device at one end of the stretch and adissimilar system used to control the traiiic controlling device at theother end.

Although I have herein shown and described only one form of apparatusembodying my in vention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. A railway signal system including, a stretch of railway trackarranged in track sections, signals located at intervals for governingtraffic in one direction through the stretch and other signals locatedat intervals for governing traffic in the other direction through thestretch, a directional relay for each signal adapted when energized toclear said signal, circuit means to control the directional relaysarranged to effect the energizing of the relays associated with thesignals governing traiiic in a given direction only when each tracksection is unoccupied and each signal governing traflic in the oppositedirection is at stop, and means effective when the directional relaysfor a given direction of traffic are energized to retain said relaysenergized irrespective of the traffic conditions of the track sections.

2. A railway signal system including, a stretch of railway trackarranged in track sections, signals located at intervals for governingtrafiic in one direction through =the stretch'and other signals locatedat intervals for governing 'trafiic in the other direction through thestretch, a directional relay for each signal adapted when energized toclear said signal, circuit means to control the directional relaysarranged to eficct the energizing of the relays associated with thesignals governing trafiic in a given direction only wheneach tracksection is unoccupied and each signal governing traffic in the oppositedirection is at stop, and means effective when the directional relaysfor a given direction of traffic are energized to retain said relaysenergized irrespective of the traffic conditions of the track sectionsor of the position of the opposing signals.

3. A railway signal system including, a stretch of railway trackarranged in track sections, signals located at intervals for governingtraflic in one direction through the stretch and other signals locatedat intervals for governing traific in the other direction through thestretch, a directional relay for each signal adapted when energized toclear said signal, circuit means to control the directional relaysarranged to effect the energizing of the relays associated with thesignals governing trafiic in a given direction only when each tracksection is unoccupied, and a stick circuit for each relay efiective whenthe directional relays for a given direction of traflic are onceenergized to retain its relay energized irrespective of the trafficconditions of the track sections.

4. A railway signal system including, a stretch of railway trackarranged in track sections, signals located at intervals ion-governingtraffic in one direction through the stretch and other signals locatedat intervals for governing tramc in the other direction through thestretch, a directional relay for each signal-adapted when energized toclear said signal, a manually'controlled circuit means to control thedirectional relays capable of energizing the relays associated with thesignals governing traffic in one direction orenergizingthe relaysassociated with'the signals governing traffic in the other directiononly when-each track section is unoccupied, and thereby clear thesignals for one direction or the other, and a stick circuit 'for eachrelay effective when'the directional relays for a given direction oftraflic ar'eonce'energized toretain its relay energized irrespectiveof'the traflic conditions of the track sections.

5. A railwaysignal system including, a stretch of railway, signalslocated at opposite ends of the "stretch to govern trafiic in oppositedirec- "tions through the stretch, a control circuit for each signalresponsiveto traffic conditions'ofthe stretch, a traiiic directioncontrolling circuit, a

directional relay for each signal adapted when energized to clear thesignal controlled jointly by the traffic direction controlling circuitand the control circuit for the same signal, means -rendered effectiveto control=a directional relay by the traflic direction controllingcircuit only,

once the relay is energized, and'a manually operated device to controlthet'raflic direction controlling circuit.

6. A railway signal system'including, a stretch of railway,signalslocated 'atopposite ends ofthe stretch to govern tr'afiic inopposite directions throughthe stretch,-a c'ontrol circuit for eachsignal "responsive 'to trafiic conditions of the stretch, a directionalrelay for each signaL-a' traffic direction controlling circuit, meanscontrolled jointlyby the control-circuit of a signal and the trafiicdirection controlling circuit to "energize the directional relayassociated with'that-signal, means controlled jointly-by the controlcircuit and the directional relay to clear the "signal, means to a'nnulthe'control of'the control circuit over the directional relay once saidrelay-is set to clear its signal, andmanuall'y operated devices tocontrol said trafiic direction controlling circuit.

7. A railway signal: system including; a' stretch of; railway arrangedin a plurality of track blocks, a signal located at each-end of a trackblock to govern traffic in opposite directions-through the block, atrafiic direction controlling circuit for each track block forcontrolling the-signals, traffic controlled means for each track blockresponsive to traflic conditions of the block, arnanually operateddevice adapted to act in conjunction with the trafiic controlledmeans'for causing the traffic direction controlling circuits toestablish a given direction of traflic through the stretch, and meansassociated'with'each trafiic direction controlling circuit to annul thecontrol of the trafiic'controlled means over said tramc directioncontrolling circuit once the direction of trafiic has been established.

8. A railway signal system including-a stretch of railway arranged in aplurality of track-blocks, a signallooated at each end of atraclrblockto governtraffic in opposite directions through the block, atraffic'direction controlling-circuit' for each track block forcontrolling the. signals; traffic controlledvmeansfor eachtrackblock-responsive to ,trafiic conditions of the block/1 a circuitcontrolling device for each signal governed by the position of thesignal, a manually operated device adapted to act in conjunction withthe traflic controlled means and the circuit controlling devices forcausing the trafiic direction controlling circuits to establish a givendirection of trafiic through said stretch, and means associated witheach traflic direction controlling circuit to annul the control of thetrafiic controlled means and the circuit controlling devices over saidtraffic direction controlling circuit once the direction of traffic hasbeen established.

9. A railway signal system including, a stretch of railway over whichtrafiic normally moves in either direction, a first set of signalslocated at intervals to govern trains through the stretch in onedirection, a second set of signals located at intervals to govern trainsthrough the stretch in the opposite direction and arranged that there isa signal of the second set located opposite each signal of the firstset, traflic direction controlling circuit means to selectively controlsaid first and second set of signals arranged to clear the signals of aset by starting at the remote end of the stretch and clearing thesignals successively, a signal device controlling said traffic directioncontrolling circuit means to check the stop indication of the opposingsignal of each of the successive signals of the set selected before thesignal can be cleared, and means controlled by said trafiic directioncontrolling circuit means to annul the control of said traiiic directioncontrolling circuit means by said signal device once a set of signalshas been cleared.

10. A railway signal system including, a stretch of railway, a first setof signals located at intervals to govern tramc in one direction throughthe stretch, a second set of signals located at intervals to governtrafiic in the opposite direction through the stretch, a control circuitfor each signal responsive to trafiic conditions in advance of thesignal, and a manually controlled circuit means to establish thedirection of traffic adapted to act in conjunction with the controlcircuits to selectively clear one or the other of saidset of signalswhen said stretch is unoccupied to permit a train to enter said stretch,said manually controlled circuit means capable of reversing thedirection of trafiic to the rear of a train occupying any intermediatepoint of the stretchand act in conjunction with the control circuits toclear the opposing signals in the rear of saidtrain and thereby permit atrain to travel in the reverse direction from said intermediate point.

11. A railway signal system including, a stretch of railway, a first setof signals located at intervals to govern traffic in one directionthrough the stretch, a second set of signals located at intervals togovern traffic in the opposite direction through the stretch, a trackcircuit for each signal responsive to trafiic conditions in advance ofthe signal, and a manually controlled means to establish the directionof traffic adapted to act in conjunction with the track circuits toselectively clear one or the other of said set of signals when saidstretch is unoccupied to permit a train to traverse said stretch, saidmanually controlled means capable of reversing the direction of trafficto the rear of a train occupying any intermediate point of the stretchand cooperate with said track circuits to clear the opposing signal tothe rear of said train and thereby intervals to govern traffic permittraffic in the reverse direction from said intermediate point.

12. In combination, a stretch of railway track, a signal at each end ofthe stretch to govern trafic in opposite directions through the stretch,a trafiic locking circuit for the stretch divided into a plurality ofdifferent sections, a source of current and a relay at each end of thestretch, manually controlled means at each end of the stretch to connecteither the current source or the relay at such end to the trafiiclocking circuit, repeating means at each junction of adjacent sectionsof the traiiic locking circuit including two directional relayscontrolled by said circuit and arranged to supply current to theleft-hand section in response to control by current from the right-handsection or to supply current to the right-hand section in response tocontrol by current from the left-hand section for energizing the relayat the end of the stretch opposite that at which the current source isconnected to the trafiic locking circuit, and means controlled by therelay at each end of the stretch for governing the signal located at itsend.

13. A railway signal system including, a stretch of railway, a first setof signals located at intervals to govern traffic in one directionthrough the stretch, a second set of signals located at intervals togovern traffic in the opposite direction through the stretch, a signalcontrol circuit for each signal responsive to trafiic conditions inadvance of the signal, a trafiic control circuit for each signal,manually controlled means for governing the trafiic control circuits toselect the direction of traffic, and means controlled jointly by thetraific control circuits and the signal control circuits to selectivelyclear the set of signals corresponding to the direction selected by themanually controlled means, and said traffic control circuits arranged insuch a manner as to permit the manually controlled means to reverse thedirection of trafiic to the rear of a train occupying any intermediatepoint of the stretch whereby the signals will be cleared for a train tomove in the reverse direction from said intermediate point.

14. A railway signal system including, a stretch of railway, a first setof signals located at in one direction through the stretch, a second setof signals located at intervals to govern trafiic in the oppositedirection through the stretch, a control circuit for each signalresponsive to trafiic conditions in advance of the signal, a trafficcontrol circuit for the stretch and divided into a plurality ofdifferent sections, two directional relays located at each junction ofadjacent sections of the trafiic control circuit, manually controlledmeans to govern the trafiic control circuit to selectively energize thedirectional relays at each junction to establish the direction oftraffic, means controlled jointly by the directional relays and saidcontrol circuits to selectively clear one set or the other of saidsignals, and said traific control circuit arranged in such a manner asto permit the manually controlled means to reverse the selection of thedirectional relays at all junctions to the rear of a train occupying anyintermediate point of the stretch whereby the opposing signals may becleared for a train to move in the reverse direction from saidintermediate point.

JAMES A. PARKINSON.

